All quality Portable Ultra Sonic Flow Meters available today, work very well. If there is an issue or question on a measurement result, internal sub-routines within the handheld usually provide sufficient feedback information on the process and the meter setup to provide the user a reasonable verification of the system's operation. If the connecting cables are suspect, a simple multi-meter test will verify cable continuity. However, if the transducers are suspect, there has not been, to this point in time, an accepted method of confirming transducer operation or the overall system's operation, short of an expensive flow lab verification of the metering system . The PRS-50 addresses that! Click here to download the data sheet.